If there was ever any doubt (there wasn't), it is now over: the election was rigged, and not just the 50 cities and 3 million votes that the Guardian Council admits were fraudulent. No, it was much more pervasive than that:
In a third of all provinces, the official results would require that Ahmadinejad took not only all former conservative voters, and all former centrist voters, and all new voters, but also up to 44% of former Reformist voters, despite a decade of conflict between these two groups.
Much more at Juan Cole's. Here is the study itself [pdf].